1. Technical Field
Example embodiments relate to nonvolatile memory devices. More particularly, example embodiments relate to methods of programming nonvolatile memory devices including multi-level cells.
2. Description of the Related Art
Memory cells of a nonvolatile memory device, such as a flash memory device, may be classified into single level cells (SLCs) that store one bit of data per memory cell and multi-level cells (MLCs) that store more than one bit of data per memory cell. The MLCs may store multiple bits of data by using multiple threshold voltage distributions to represent different states of multi-bit data. For example, two-bit MLCs may use four threshold voltage distributions to represent respective logical states “11”, “10”, “01” and “00”.
To ensure accurate storage of the multi-bit data, the threshold voltage distributions of the MLCs must be separated by adequate sensing margins. However, certain aspects of newer flash memory devices, such as increasing integration density, may cause the threshold voltage distributions to widen due to electrical coupling between adjacent memory cells or a program disturb.